1. Field of the Invention
The present invention relates to an optical power measurement apparatus and an optical power measurement method for measuring the power of an optical signal in a WDM communication system.
2. Description of the Related Art
To fulfill the requirement for an increased capacity of a backbone communication network in response to the increase in communication traffic in recent years, there is commercialized a WDM (Wavelength Division Multiplexing) communication system having a transmission rate of 10 Gbps per wavelength (hereinafter referred to as 10 G in some cases). However, the ever increasing communication traffic drives research and development on high-speed communication systems having a transmission rate of 40 Gbps (hereinafter referred to as 40 G in some cases).
In such WDM communication systems, it is necessary to measure the power of optical signals to control, for example, the output power of optical amplifier in a optical repeater node. A typical method for measuring the power of optical signals is to use an optical spectrum analyzer to measure the power in the frequency domain.
Since a modulated optical signal has a broader optical spectrum, it is necessary to measure at a wavelength resolution appropriate for the optical spectral width of the optical signal to measure the power accurately. Furthermore, since the optical spectral width of an optical signal propagating at a higher speed is typically broader, it is necessary to measure a high-speed optical signal at a broader wavelength resolution.